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The invention is concerned with liquid oral prebrushing compositions containing sodium benzoate, sodium lauryl sulfate and small but effective amounts of tetrasodium pyrophosphate. These compositions are designed for removal of plaque from teeth before brushing with a dentifrice. Dental plaque is a problem with the teeth of most persons and consists of a microbial film which adheres firmly to dental surfaces. While it often can be removed with some difficulty by surface cleaning, it has a tendency to reform rapidly so continuous treatment is needed.
Plaque is particularly dangerous when formed on the teeth around the gum surface as it leads to gingivitis, periodontal disease and eventually loss of teeth and jawbone.
While many people can obviate most plaque problems by daily brushing and flossing combined with periodic cleaning by a dental hygienist, for some this is not sufficient. Therefore, it is desirable to have an oral composition which can be used on the teeth prior to brushing to soften and loosen the plaque so that it is more easily removed by the physical abrasion of brushing.
U.S. Pat. No. 5,338,538 uses a combination of pyrophosphate and sodium lauryl sulfate in a prebrushing oral formulation for softening and removal of plaque. The compositions of this patent all have a relatively high concentration of pyrophosphate salt and also operate at an alkaline pH, and tend to have a problem with clouding when stored at cooler temperatures.
The present invention relates to a liquid oral prebrushing composition designed to loosen and remove accumulated plaque deposits, has a slightly acidic pH of about 5.0 to less than 7.0, and contains sodium benzoate, sodium lauryl sulfate and tetrasodium pyrophosphate. The composition remains clear and uniform without any indication of clouding or precipitation when stored in temperatures of 7xc2x0 C. to 40xc2x0 C. for prolonged periods.
The invention preferably is a clear solution comprising about 6.0 to about 10.0 wt. % ethyl alcohol, about 5.0 to about 15 wt. % of a selected humectant, preferably glycerin or sorbitol, about 0.02 to about 0.075 wt. % sodium lauryl sulfate, about 0.2 to about 0.85 wt. % sodium benzoate, an acid buffer to pH at about 5.5 to about 6.5, sodium saccharin to the desired sweetness level, selected flavors, a soluble thickener which may be added at 0.001 to 0.10 wt. %, and D.andC. or F.D.andC. dyes, as required. Sodium fluoride can be incorporated at a safe and effective level to make the product also a post-brushing rinse. About 0.01 to about 0.05 wt. % tetrasodium pyrophosphate, with the other detergent salts, i.e., sodium benzoate and sodium lauryl sulfate, are effective in loosening and assisting in removing accumulated oral plaque when the product is rinsed over dental surfaces prior to a vigorous brushing.
The most effective manner of combining the foregoing ingredients to provide a clear, stable product is as follows:
1. All alcohol soluble ingredients; namely the solubilizers, benzoic acid, and flavors are added to and mixed into the ethyl alcohol.
2. A separate slurry is prepared by dissolving the sodium lauryl sulfate in a portion of the batch water, adding the soluble gum thickener and mixing until clear.
When clear and uniform, the selected humectant (glycerin or sorbitol solution) can be added and mixed until uniform.
3. The major portion of the purified water is charged into the manufacturing tank, mixing is started and the balance of the water soluble materials are added, namely, sodium benzoate, tetrasodium pyrophosphate, sodium saccharin, dyes, sodium fluoride, if desired, and the balance of the humectant. This is then mixed until uniform. The alcohol phase is next added and mixed. The gum slurry is added and, after mixing until uniform, the batch is completed with purified water, mixed and sampled for specification testing.